1. Field of the Invention
This invention relates to photographic elements having a colloid-silver halide emulsion layer on a colloid or polymer substrate (e.g., a subbed or unsubbed film support) having after development improved anchorage of the silver image to the substrate. More especially, it relates to silver halide photographic elements intended to be developed by the use of tanning developing agents and thereafter subjected to additional treatment to remove unexposed and unhardened areas, and to a development process therefor.
2. Description of the Prior Art
It is a long-standing common practice in the photographic art to coat a colloid-silver halide emulsion on a polymeric film support or to employ an intermediate subbing layer between the emulsion and the support to improve the anchorage of the emulsion to the support. The subbing layer may be a thin coating of a dilute solution of a colloid such as gelatin or it may be a coating of any of a large number of polymeric compositions disclosed in the art for this purpose. The anchorage provided in this way is adequate for many uses but is not always entirely sufficient, especially for films of the wash-off variety, such as are used for drafting films as described, for example, in Moede, U.S. Pat. No. 3,353,958, stripping films, printing plates, resists, and the like. The processing of materials of this kind ordinarily includes a step wherein the exposed and developed film is subjected to a spraying or scrubbing action with water or other liquids to remove the emulsion from the support in the unexposed areas. The silver image, which is intended to be retained on the support, is relatively easily damaged and can be at least partially removed when the spraying or scrubbing action is sufficiently vigorous. Thus, there has been a need to provide anchorage to a degree greater than that offered by prior art subbing layers, particularly for wash-off films of various kinds.